The present disclosure relates to methods for manufacturing an electrostatic latent image developing toner.
For the purpose of enhancing the quality of images to be formed, recent demands for toner are to reduce the average particle size of toner particles thereby to increase the resolution. To output images of high quality, it is effective to reduce an average particle size of toner and to ensure that the particle size distribution of the toner is sharp.
For manufacturing toner having a small average particle size and a sharp particle size distribution, one known method involves a process of preparing a dispersion liquid containing particulates and a process of forming aggregated particulates. In this method, the process of preparing the dispersion liquid involves application of a mechanical shear force to a particle-like mixture containing a binder resin and a colorant in an aqueous medium. As a result, the dispersion liquid containing particulates is prepared. The process of forming aggregated particulates involves adjusting the pH of the dispersion liquid to cause the particulates contained in the dispersion liquid to aggregate. When the pH of the dispersion liquid is 7, the volume average particle size of the particulates contained in the dispersion liquid is 2 μm or less, and when the zeta-potential of the particulates is −30 mV, the pH of the dispersion liquid is 3.0 or more and 6.9 or less.
In another known method that is based on the above-described method, the process of forming the aggregated particulates involves adding a dispersion liquid that additionally contains particulates containing resin. With such a method, shell layers are formed each on the surface of aggregated particulates with the particulates containing the resin, so that a toner having a core-shell structure is obtained.